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Commit c9aba143 authored by Jean Delvare's avatar Jean Delvare
Browse files

firmware: dmi_scan: Look for SMBIOS 3 entry point first 



Since version 3.0.0 of the SMBIOS specification, there can be
multiple entry points in memory, pointing to one or two DMI tables.
If both a 32-bit ("_SM_") entry point and a 64-bit ("_SM3_") entry
point are present, the specification requires that the latter points
to a table which is a super-set of the table pointed to by the
former. Therefore we should give preference to the 64-bit ("_SM3_")
entry point.

However, currently the code is picking the first valid entry point
it finds. Per specification, we should look for a 64-bit ("_SM3_")
entry point first, and if we can't find any, look for a 32-bit
("_SM_" or "_DMI_") entry point. Modify the code to do that.

Signed-off-by: default avatarJean Delvare <jdelvare@suse.de>
parent 3c2993b8

drivers/firmware/dmi_scan.c

+16 −1
Original line number Diff line number Diff line
@@ -649,6 +649,21 @@ void __init dmi_scan_machine(void) 
		if (p == NULL)

			goto error;



		/*

		 * Same logic as above, look for a 64-bit entry point

		 * first, and if not found, fall back to 32-bit entry point.

		 */

		memcpy_fromio(buf, p, 16);

		for (q = p + 16; q < p + 0x10000; q += 16) {

			memcpy_fromio(buf + 16, q, 16);

			if (!dmi_smbios3_present(buf)) {

				dmi_available = 1;

				dmi_early_unmap(p, 0x10000);

				goto out;

			}

			memcpy(buf, buf + 16, 16);

		}



		/*

		 * Iterate over all possible DMI header addresses q.

		 * Maintain the 32 bytes around q in buf.  On the
@@ -659,7 +674,7 @@ void __init dmi_scan_machine(void) 
		memset(buf, 0, 16);

		for (q = p; q < p + 0x10000; q += 16) {

			memcpy_fromio(buf + 16, q, 16);

			if (!dmi_smbios3_present(buf) || !dmi_present(buf)) {

			if (!dmi_present(buf)) {

				dmi_available = 1;

				dmi_early_unmap(p, 0x10000);

				goto out;